A beam combiner is needed e.g. in a display device that can be fitted onto the head of a user, in order to be able to present to the user a generated image superimposed on the perceptible surroundings. The beam combiner is often formed as a curved spectacle lens in this case.
It is known to realize a beam combining through a semi-transparent mirror. However, the production technique is difficult, in particular if the light of the generated image is guided in the glass and the glass is curved.
Furthermore, a beam combining can be effected by means of an optical grating. However, this often disadvantageously involves undesired scattered light due to additional diffraction orders. Furthermore, such a grating is often only very narrow-band, with the result that the generated image can be only monochrome.